1. Field of the Invention
This invention relates to an electronic calculator which displays a mathematical formula in such a natural way as written in a textbook.
2. Description of the Related Art
In many conventional scientific electronic calculators, the representational form of the mathematical formula keyed in by the user or its calculation result was such that the formula or the result was displayed in one line according to the display capability of the display unit.
For example, when a square-root formula is input, since the range covered by a root “√{square root over ( )}” cannot be displayed in a mathematically natural form, the root sign “√{square root over ( )}” is combined with such signs as parentheses or braces and the resulting formula is displayed as, for example, “√{square root over ( )}(2)” in a line.
Similarly, when a mathematical formula including a fraction is input, a numerator and a denominator cannot be displayed above and below the division sign, respectively, in a mathematically natural form. Therefore, they are displayed as “A/B” in a line.
Against this backdrop, a scientific electronic calculator capable of displaying a mathematical formula in a mathematically natural way as written in a math textbook has been disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2007-264765.
The scientific electronic calculator capable of mathematically natural display has an intake input function of keying such a function as “√{square root over ( )},” “a/b,” or “sin” into a mathematical formula keyed-in and displayed to edit the formula.
In the specification of the intake input function, for example, a cursor is positioned between “A” and “(B” in the formula “A(B+C)(D+E)” and “insert” key for intake and “√{square root over ( )}” key are input, causing the formula part (B+C) immediately after the cursor position where “√{square root over ( )}” was input to be taken in as the range covered by “√{square root over ( )}” and the horizontal line of the √{square root over ( )} sign to be extended over (B+C), which enables the formula to be edited.
Furthermore, for example, when the cursor is positioned between “C)” and “(D” in the formula “A(B+C)(D+E)” and “insert” key for intake and “a/b” key are input, the formula part (B+C) immediately before the cursor position in which “a/b” key was input and the formula part (D+E) immediately after the cursor position are taken in as the range of the numerator and denominator covered by “a/b,” causing (B+C) to be displayed above the division sign and (D+E) to be displayed below the division sign, which enables the formula to be edited.
As described above, the scientific electronic calculator enables such a function (2D (two-dimensional) function) as root “√{square root over ( )}” or fraction “A/B” to be displayed in mathematically natural notation. However, in a function intake input, such as root “√{square root over ( )}” or fraction “a/b,” since the range taken in so as to cover the input function is restricted to a minimum formula part immediately before and after the function, a sufficient range of the formula cannot be taken in.
According to the invention, there is provided an electronic calculator capable of, when taking in a function needing mathematically natural notation, taking in a sufficient range covered by the function.